Avalanches still possible, even likely, with thin snowpack

By Emily Stifler, Explorebigsky.com Managing Editor

With La Nina off to a slow start, our mountain snowpack is thin but still skiable. Enough snow to slide on means enough snow to avalanche.

Like Thanksgiving leftovers in the back of the fridge, the early snow that fell in late October and stuck on high slopes has rotted out, turning to a weak layer of sugary facets near the ground.

That weak layer crusted over in some places, and then was buried by mid-November snows. Wind piled heavy slabs atop that in many alpine areas, creating a perfect recipe for avalanches: heavy on top, weak on the bottom.

Since then, warm temps in late November helped stabilize slopes in places like Bacon Rind, the Lionhead and Beehive Basin. “However, it is still possible to trigger slides in these areas,” according to a Nov. 28 avalanche bulletin from the Gallatin National Forest Avalanche Center.

In the northern Gallatins and the mountains around Cooke City, both of which had deeper snow, the warmer temps did not affect the weak facets in the same way. Accordingly, these ranges have both seen notable natural avalanche activity.

The avalanche center warns that steep, upper elevation slopes, specifically those that have been wind loaded, are particularly dangerous.

“Thinner, early season snowpacks, tend to catch people off guard,” said Eric Knoff, a GNFAC forecaster. “Just because it’s shallow, doesn’t mean it’s necessarily safe.”

“People are going to start venturing further and deeper in the backcountry in search of [better conditions], because the lower elevations go worked with this warm weather.” That’s where Knoff imagines someone getting into trouble.

Knoff wanted to drive home the point “that avalanches are highly unpredictable, and that it’s still very possible to trigger slides in the backcountry.”

So, what happens when it snows?

It all depends on how much, and how quickly that snow comes, says Mark Staples, another GNFAC forecaster.

“If we just get a little bit of snow, the danger won’t go up too much. If we get a lot, it’ll go up more… This is because when a lot of snow accumulates quickly, the snowpack doesn’t have time to adjust to the load. “We tend to see a lot of avalanches anyway, when we get a big, rapid, heavy load, no matter what’s happening in the snowpack,” he added.

“If we could just turn on the snow hose and let it come in a few inches every day, that would be ideal,” he said, explaining that a slow steady build-up of snow, combined with mild temperatures, would allow that weak layer near the ground to gain strength over time.

And what about La Nina? NOAA’s long-range climate-based forecast calls for slow building this winter. So while we wait, it’s a good time to practice with rescue gear.

Knoff wanted to remind skiers of the three key rules of backcountry travel: Carry rescue gear; always watch your partner; and never put more than one person on a slope at the same time.